1. The purpose of this study is
to evaluate the performance
of Green Infrastructure (GI) in
improving stormwater quality.
Green infrastructure design
focuses on uses ecological
principles to provide
infrastructure services.
Current literature suggests
significant performance
benefits of GI design;
however, there is a
regional disparity, in
respect to number of GI
projects reported, level of
sophistication in design,
available design guidelines,
and policy endorsement. This
study looks to fill a gap in case-
studies within the arid west region.
Our study site is the 4,100 acre master-
planned community of Daybreak in
South Jordan.
This development uses a variety
of techniques to manage all of its
stormwater on-site, including canals,
dry wells, constructed wetlands,
bioswales and infiltration basins with
no impacts on or connections to
the municipal storm sewer system.
Two adjacent sub-watersheds were
chosen to compare the relative
effectiveness of different stormwater
Preliminary results are very favorable to GI, showing
the bioswale watershed outperforming the traditional
detention basin system in removing every pollutant
measured (see Figure 2). However, the most significant
finding being the removal of heavy metals, in
particular Copper as this is notoriously difficult to
remove from water. The first flush shows 92% fewer
suspended solids, 87% less total Nitrogen, 92% less total
Phosphorus, 96% less Zinc & Lead, and 82% less Copper
than the traditional stormwater system.
management techniques.
One watershed incorporates
GI strategies including a
series of vegetated bioswales
to filter runoff. The
other watershed utilizes
traditional stormwater
management methods
and uses stormwater
drains to direct runoff
into a detention basin.
This site is of interest
not only because of
the extensive use of
GI, but its adjacency to
Bingham Copper Mine.
A sampling station was
set up at the outlet of each
watershed where the stormwater samples are collected.
Each station has a solar powered automated ISCO 6712
sampler to collect runoff after storm events. The ISCO
pump is activated by a flow sensor, located within the
culvert, that signals the pump to draw samples. As
long as the sensor detects sufficient flow the sampler
collects water at predefined intervals and stores them
in plastic bottles within the apparatus. Samples are
analyzed by the Utah Water Research Laboratory for
a variety of contaminants, including: total suspended
solids (TSS), heavy metals, total nitrogen (TN) and
phosphorus concentrations (TP). The detention basin
watershed station collects samples before the outlet
into the detention basin, and thus reflects a grey
infrastructure paradigm.
GREEN INFRASTRUCTURE
PERFORMANCE IN STORMWATER QUALITY
INTRODUCTION
METHODS
RESULTS
VSGREY GREEN
TSS
TN
TP
Cu
Pb
Zn
4500 4500
Parts per billion
VSGREY GREEN
TSS
TN
TP
Cu
Pb
Zn
4500 4500
Parts per billion
Not only are GI systems effective at reducing pollutants
in stormwater runoff, they have the added benefit
of being less expensive, lower maintenance and are
more sensitive to the pre-existing hydrology of the
site. If similar systems were implemented throughout
the state it would greatly increase stormwater quality
allow groundwater recharge and reduce reliance on
municipal stormwater treatment systems.
CONCLUSION
Many thanks to the research team past & present, Pam Blackmore, Luigi
Dragonetti, Sam England, Tim Bowler, Graydon Bascom, & Grant Hardy
ACKNOWLEDGMENTS
Hailey Wall & Dr. Bo Yang
Department of Landscape Architecture & Environmental Planning
Email: hailey.wall@aggiemail.usu.edu or bo.yang@usu.edu
This research was supported by the Utah Agricultural Experiment
Station, Utah State University and the NSF EPSCoR grant EPS 1208732
awarded to Utah State University, as part of the State of Utah Research
Infrastructure Improvement Award. Any opinions, findings, and
conclusions or recommendations expressed are those of the authors
and do not necessarily reflect the views of the Utah Agricultural
Experiment Station and the National Science Foundation.
Figure 1. Bioswale Diagram
BIOSWALES
are vegetated,
mulched, or
xeriscaped channels
that provide
treatment and
retention as they
move stormwater
from one place to
another. Vegetated
swales slow,
infiltrate, and filter
stormwater flows.
How do bioswales
compare with
traditional methods??
BIOSWALE SAMPLING STATION
DETENTION SAMPLING STATION
Figure 3. Context Map
BIOSWALE
WATERSHED
DETENTION BASIN
WATERSHED
DAYBREAK
$$
$$ Green Infrastructure costs
on average 20-35% less than
traditional infrastructure
$$